Computers will someday compress entire libraries onto chips or discs and, thereby, open vast vistas of information to almost anyone. The trouble with this is arithmetic and common sense. A school library with 2,000 books can theoretically serve 2,000 readers simultaneously. A school library with one computer terminal that can call up 200,000 books can serve only one reader at a time. The computer creates a bottleneck. Sure, the library can buy more computers, but they’re costlier and bulkier than books. Finally, there’s common sense: Do most people really need access to, say, the entire collection of the New York Public Library?